Isopropenyl chlorocarbonate (IPCC)1 in amino acid and peptide chemistry: Esterification of N-protected amino acids; Application to the synthesis of the depsipeptide valinomycin
Esterification of N-protected α-amino acids was achieved via isopropenyl chlorocarbonate (IPCC) activation. In situ alcoholysis of the unstable mixed anhydride intermediate was catalyzed by 4-(dimethylamino)pyridine (DMAP). Competing isopropenyl ester formation was negligible when using methylene chloride as the solvent. A variety of esters from primary and secondary alcohols were obtained with good
range of substrates, yet retain high selectivity. In this work, we propose a hapten design to endow antibody catalysts with two opposing qualities, such as high enantioselectivity and broad substrate specificity. Racemic hapten 2 induced two separate classes of catalytic antibodies to hydrolyze either the l- or d-isomers of N-Cbz-amino acid esters 1. In the kinetic resolution of racemic ester 9, antibodies
The extremely low efficiency during the α-chymotrypsin-catalyzed coupling of an inherently poor amino acid substrate, e.g., alanine, using the methyl ester as an acyl donor was significantly improved using esters such as the 2,2,2-trifluoroethyl or carbamoylmethyl ester. The ameliorating effect of the latter ester was especially significant.
CATALYTIC ANTIBODY WHICH HYDROLYZES AMINO ACID ESTER DERIVATIVE ENANTIOSELECTIVELY
申请人:PROTEIN ENGINEERING RESEARCH INSTITUTE
公开号:EP0765940A1
公开(公告)日:1997-04-02
Optical resolution of amino acid racemates and preparation of optically active amino acids with the use of a catalytic antibody which hydrolyzes amino acid ester derivatives enantioselectively; a catalytic antibody used therefor; and a hybridoma which produces the antibody. Typically, this antibody is produced by effecting antigenic stimulation using the compound (3) as the hapten, wherein CBZ stands for N-benzyloxycarbonyl.